Zack Wheeler underwent surgery and his return to the Philadelphia Phillies for the postseason is unclear after manager Rob Thomson said he has "no timetable" for the right-hander's return.

The Phillies announced Wheeler had a successful "thrombolysis procedure to remove a blood clot in his right upper extremity" on Monday. There were no immediate answers to when Wheeler would be back on the mound or if additional treatment could be necessary.

"I'm thinking a lot about Zack and his family because this is not a hamstring injury or something like that," Thomson said.

Wheeler was placed on the 15-day injured list Saturday due to a blood clot located near his right shoulder. He previously missed another start and was subtracted from the rotation one day after he allowed two runs on four hits over five innings in Friday's 6-2 win over the Washington Nationals. It also came as the Phillies were working Aaron Nola back into the starting mix following three months on the IL, with plans to utilize a six-man rotation.

"There's not a whole lot we can say on it at this time," team president Dave Dombrowski said Saturday.

Wheeler was an All-Star each of the past two seasons. In six seasons with the Phillies, the right-hander is 69-37 with a 2.91 ERA and 1,094 strikeouts to 220 walks in 979 innings.

In 24 starts this season, he is 10-5 with a 2.71 ERA and a National League-leading 195 strikeouts.

Before arriving in Philadelphia, Wheeler spent five seasons with the New York Mets.

Nola was activated from the 60-day IL on Sunday morning. He will take over the vacant spot in a traditional five-man rotation.

Nola, a former All-Star, posted a 3.57 ERA in 33 starts last season, but he got off to a rough start in 2025 and has a 6.92 ERA through 10 starts. He has battled ankle and rib injuries.